Core A is a combined clinical and scientific core that will primarily be responsible for recruiting normal volunteers and patients to serve as donors of peripheral blood cells and bronchoalveolar lavage (BAL) cells for the individual projects. Peripheral blood mononuclear cells will be collected and separated into purified populations of resting T cells and monocytes by centrifugal counterflow elutriation. Alveolar macrophages will be collected by BAL. Cells will be characterized by immunofluorescent antibody staining prior to distribution to the investigators. The core will maintain a database of clinical information and the results of experiments in the individual projects for correlation. The core will also function to provide purified DNA fragments and riboprobes for hybridization experiments and synthetic oligonucleotides for use as polymerase chain reaction primers (Project 4) and for site-directed mutagenesis (Project 1).